Re: [HMM v16 01/15] mm/memory/hotplug: convert device bool to int to allow for more flags v2

[Jerome Glisse]

On Fri, Jan 13, 2017 at 07:27:41PM +0530, Balbir Singh wrote:
> On Thu, Jan 12, 2017 at 11:30:28AM -0500, Jérôme Glisse wrote:
> > When hotpluging memory we want more informations on the type of memory and
> > its properties. Replace the device boolean flag by an int and define a set
> > of flags.
> > 
> > New property for device memory is an opt-in flag to allow page migration
> > from and to a ZONE_DEVICE. Existing user of ZONE_DEVICE are not expecting
> > page migration to work for their pages. New changes to page migration i
> > changing that and we now need a flag to explicitly opt-in page migration.
> 
> Given that ZONE_DEVICE is dependent on X86_64, do we need to touch all
> architectures? I guess we could selectively enable things as we enable
> ZONE_DEVICE for other architectures?

Yes i need to change all architecture because the function prototype changes.

I add the bug stuff to be bullet proof from new feature added that might
cause trouble if arch does not handle them explicitly. If the bug stuff scares
people i can remove it.

Cheers,
Jérôme